System identification analyses are used to evaluate soil-structure interaction effects for 77 strong motion data sets at 57 building sites that encompass a wide range of structural and geotechnical conditions. Kinematic interaction effects on the \"input\" motion at the bases of structures are found to be relatively modest in many cases, whereas inertial interaction effects on the structural response to these motions can be significant. To quantify inertial interaction effects, fixed- and flexible-base modal vibration parameters are used to evaluate first-mode period lengthening

Closure of "Seismic Soil-Structure Interaction in Buildings. II: Empirical Findings"

A new approach for longitudinal vibration of a large-diameter floating pipe pile in visco-elastic soil considering the three-dimensional wave effects

Stiffness and load sharing characteristics of piled raft foundations subjected to dynamic loads

In recent years, the high development of high-speed railway lines cross through areas with poor geological conditions, such as soft soil, offshore and low-lying marsh areas, resulting geotechnical problems, such as large settlements and reduction of bearing capacity. As a new soil reinforcement method in high speed railway lines, the piled raft structure has been used to improve soil conditions and control excess settlement. In order to study the dynamic behavior of piled raft supported ballastless track system in soft soil, an experimental study on vibration velocities of piled raft supported embankment and foundations is presented in soft soil with different underground water levels. Vibration velocities at specified positions of the piled raft supported embankment and foundations are obtained and discussed. The vibration velocity curves on various testing locations of piled raft foundations are clearly visible and have sharp impulse and relaxation pattern, corresponding to loading from train wheels, bogies, and passages. Vibration velocity distribution in the horizontal direction at three train speeds clearly follows an exponential curves. Most of the power spectrums of vibration velocity at various locations are mainly concentrated at harmonic frequencies. The change in water level has slight impaction on the peak spectrum of vibration velocity at harmonic frequencies. The vibration power induced by train loads are transmitted, absorbed, and weakened to a certain extent through embankment and piled raft structure. The dynamic response character of embankments are affected by their self-vibration characteristics and the dynamic bearing capacity of the piled raft structure.

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Experimental Study on Vibration Velocity of Piled Raft Supported Embankment and Foundation for Ballastless High Speed Railway

Three-dimensional numerical analysis on seismic behavior of soil-piled raft-structure system

Cyclic and postcyclic behaviour of silts and silty sands from the Indo Gangetic Plain

This paper presents a study on three-dimensional seismic soil–structure interaction analysis of a piled-raft (PR) foundation in clay by the substructure approach. Two different pile modeling techni...

Seismic Response Characteristics of a Piled Raft in Clay

Piled raft foundation is gaining popularity as a composite foundation system economizing foundation design for tall, heavy structures. The seismic response of a piled raft foundation would involve complex raft–soil–pile interaction as well as pile–soil–pile interaction, which cannot be estimated efficiently by existing methods available for pile groups. This paper discusses the development of a numerical model to study the seismic response of piled raft foundation system by substructure method-based seismic soil-structure interaction (SSSI) analysis using SASSI 2010 program. The flexible volume substructure method is used to analyze SSSI problem. Published data from a centrifuge test to study earthquake response of a piled raft system in soft clay was selected for the simulation. Results from the analysis are compared with experimental data.

Ramon Varghese

Papers

Stiffness and load sharing characteristics of piled raft foundations subjected to dynamic loads

Cyclic and postcyclic behaviour of silts and silty sands from the Indo Gangetic Plain

Seismic Response Characteristics of a Piled Raft in Clay

Numerical Analysis of Seismic Response of a Piled Raft Foundation System

Investigation of pile-induced filtering of seismic ground motion considering embedment effect